pinctrl: qcom: enable generic pinconf

This makes the pinctrl driver to use the generic pinconf
interface. Mainly it gives us a way to use debugfs to dump
group configurations.

Signed-off-by: Stanimir Varbanov <svarbanov@mm-sol.com>
Acked-by: Bjorn Andersson <bjorn.andersson@sonymobile.com>
Reviewed-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>